The present invention concerns processes for the preparation of each of
the 4 diastereomers of formula (I) 1
in stereochemically pure form from either of two enantiomerically pure
precursors. The tetracyclic ringsystem having trans-fused five and seven
membered rings is formed in an acid-catalysed cyclization reaction. The
invention further relates to the thus obtained cis-fused tetracyclic
alcohol intermediates, the methanamine end-products, the methanamine
end-products for use as a medicine, in particular as CNS active
medicines.
